CODEWITHSUNDEEP
ruby-on-railsruby
user2071444
user2071444

Reputation:

Tree Nodes using array of strings

I am trying to build a tree with root, children, and grandchildren nodes using an array of strings. I have an array like this

array = [
  "/capacitor/",
  "/capacitor/non_polarized/",
  "/capacitor/non_polarized/ceramic/",
  "/capacitor/polarized/",
  "/capacitor/polarized/al/",
  "/connector/",
  "/diode/",
  "/diode/normal/",
  "/optical/",
  "/optical/emmision/diode/",
  "/optical/emmision/laser/",
  "/optical/detector/",
  "/optical/detector/diode/"
]

I would like to take this array and determine the respective nodes. The ones which are like

"/capacitor/", "/connector/", "/diode/"

are the root nodes. The ones which are like

"/capacitor/non_polarized/", "/capacitor/polarized/", "/optical/detector/"

are children nodes, and finally the ones like

"/optical/detector/diode/", "/optical/emmision/laser/"

are grandchildren nodes. A strings which has two / and text in between is a root node, with three / is a child node, and with four / is a grandchildren node.

Imagine I had capacitor as my root node, now I would have root_node = "capacitor" child_node = "/capacitor/non_polarized/","/capacitor/polarized/" and grandchild_node = "/capacitor/non_polarized/ceramic/", "/capacitor/polarized/al/"

EDIT: I would like the output in such a way that the by using the root node I can determine the children and grandchildren.

Upvotes: 0

Views: 294

Answers (3)

Benoît
Benoît

Reputation: 15010

I am sure there is a much better way to do this but if this can help you

tree = array.inject({}) do |h, string|
  values = string.split('/').reject(&:empty?)
  top = values.shift
  h[top] ||= {}
  values.inject(h[top]) do |sub_h, value|
    sub_h[value] ||= {}
  end
  h
end

y tree
#--- 
#capacitor: 
#  non_polarized: 
#    ceramic: {}
#
#  polarized: 
#    al: {}
#
#connector: {}
#
#diode: 
#  normal: {}
#
#optical: 
#  emmision: 
#    diode: {}
#
#    laser: {}
#
#  detector: 
#    diode: {}

Upvotes: 1

Benoit Marilleau
Benoit Marilleau

Reputation: 971

Here's what I would do : 

class TreeNode
  attr_accessor :name, :children

  def initialize(name, children_strings)
    @name = name
    @children = []
    @children << TreeNode.new(children_strings.shift, children_strings) if !children_strings.nil? and children_strings.count > 0
    self
  end

  def to_hash
    { name => children.map(&:to_hash) }
  end

  def self.process_node(root, strings_array)
    next_node = root.children.detect { |n| n.name == strings_array.first }
    if !next_node.nil?
      strings_array.shift
      process_node(next_node, strings_array)
    else
      root.children << TreeNode.new(strings_array.shift, strings_array)
    end
  end

  def self.process_array(array)
    root = TreeNode.new('root', nil)
    array.each do |string| 
      strings_array = string.split('/')
      strings_array.shift
      TreeNode.process_node(root, strings_array)
    end
    root
  end
end

root = TreeNode.process_array(array)

Upvotes: 0

sawa
sawa

Reputation: 168219

roots, children, grandchildren =
array.group_by{|s| s.count("/")}.values_at(2, 3, 4)

Upvotes: 1

Related Questions